Pratt truss

The Pratt truss is named after Thomas and Caleb Pratt, Boston railroad engineers who patented the design in 1844. The Pratt and its variations are the most common design of metal truss bridges.
On a basic Pratt truss, the diagonals slope toward the center of the bridge, do not cross any verticals, and are approximately parallel. The top chord is straight and parallels the lower chord. The panels can have sub-divisions - or verticals and diagonals that don't reach from the top to bottom chord, though this can be considered a variation of the basic type.
There are many variations, or sub-types of the Pratt truss, some of which have their own name including Parker, camelback, Pennsylvania, Baltimore, and others.
It is used in bridges as a through truss, pony truss, and deck truss.

Dinner Creek Bridge (Coffey County, Kansas)Built 1913Pony truss bridge over Dinner Creek on Emmer Lane, 1.5 mi. south of GridleyClosed to all traffic

Dirty Creek Bridge (Muskogee County, Oklahoma)Built 1910Through truss bridge over Dirty Creek on Ross Road. Recently Closed, due to floor beam damage.Replaced by a new bridge

Diversion Ditch Bridge (Minnehaha County, South Dakota)Built 1938 by the Western Bridge Company of Omaha, NebraskaPony truss bridge over Diversion Ditch on 257th Street, 0.3 mi. west and 1 mi. north of RennerReplaced with a culvert

DM&E - Waterworks Trestle (Scott County, Iowa)Trestle originally built in 1871, Deck girders built in the 1900s; Pony truss span built 1984 replacing the original 1917 oneTruss bridge over River Drive on Dakota, Minnesota & Eastern RailwayOpen to traffic

Donnaha Bridge (Forsyth County, North Carolina)See below in the "Description" section for a detailed history of the bridgePratt through truss bridge over Mill Creek on a private drivewayOpen to traffic

Doon Bridge (Lyon County, Iowa)Built 1900; replaced ca. 2005Lost through truss bridge over Rock River Overflow on 250th Street north of DoonRemoved; road raised to the level of the bridge; Overflow drained

Dorrington Road Bridge (Allegheny County, Pennsylvania)Built 1888 by the Pittsburgh Bridge Co.; demolished 2009Lost pony truss bridge over Robinson Run on Dorrington RoadDemolished to make way for replacement bridge

Douthit's Ferry Bridge (Bartow County, Georgia)Built 1912Pratt through truss bridge over Etowah RiverClosed to all traffic since 1985

Dowden Avenue Bridge (Delaware County, Indiana)Built ca. 1895 by the Indiana Bridge Company of Muncie; replaced in 1974Lost Pratt through truss bridge over Mississinewa River on Dowden AvenueReplaced by a new bridge

DRGW - Elk Park Bridge (San Juan County, Colorado)Built 1884; Damaged in a flood in 1964, requiring a new bridge.Pratt through truss bridge over Animas River on Abandoned RailroadReplaced by a new bridge, but left standing,

DRGW - Gunnison River Bridge (Gunnison County, Colorado)Pratt through truss bridge over Gunnison River on Denver & Rio Grande Western RailroadInundated

DRGW - Navajo River Bridge (Rio Arriba County, New Mexico)Railroad abandoned in the 50'sAbandoned through truss bridge over Navajo River on Former Denver & Rio Grande Western RailroadDerelict/abandoned

Driveway Bridge (Scott County, Kentucky)Built 1892Pratt pony truss bridge over a branch of Elkhorn Creek on a private drivewayOpen to traffic

Driveway off U.S. 212 Bridge (Carbon County, Montana)Pratt pony truss bridge over Free Silver Ditch on Driveway on Private FarmOpen to traffic on private driveway

Dubois-Cuzco Road Bridge (Dubois County, Indiana)Built in 1889 by the Mt. Vernon Bridge Company; replaced in 1987Lost Pratt through truss bridge over Patoka River on Dubois-Cuzco RoadReplaced by new bridge

Duck Creek Bridge (Mercer County, Illinois)Pony truss bridge over Duck Creek on 192nd StIntact but closed to all traffic

Duck Creek Bridge (Okmulgee County, Oklahoma)Built 1932Bedstead pony truss bridge over Duck Creek on N3910 in BeggsClosed to all traffic

Duck Creek Bridge (Brown County, Wisconsin)Built 1932; rehabilitated 1978, rehabilitated again and converted for pedestrian use 2013Riveted 6-panel Pratt through truss bridge over Duck Creek on pedestrian trail in OneidaOpen to pedestrians and bicycles only

Duck Creek CR 800N Bridge (Bartholomew County, Indiana)Built in 1904 by the Pan American Bridge Company of New Castle, INLost Pratt pony truss bridge over Duck Creek on County Road 800 NorthReplaced by a new bridge